Such networks generally include one or more service managers, each adapted to manage the execution of an associated service, i.e. the provision of said service to a terminal, for example a voicemail service, a fun tone service, a click to dial service. A plurality of service managers can be grouped together in the same application manager, which thus provides a plurality of services.
A terminal connected to the network can access one or more services offered by the network, possibly subject to a subscription appropriate to those services.
A service is generally executed by exchanging protocol messages between the associated service manager and a terminal that is generally the terminal that subscribes to the service (as happens with the voicemail and the click-to-dial services, for example) or a terminal called by the terminal that subscribes to the service. The expression “terminal that subscribes to the service” is in practice a somewhat strained use of language, referring more accurately to a terminal that is connected to the network and belongs to a user of the network who subscribes to the service concerned, said user possibly having a plurality of terminals that can be connected to the network to use the same service.
The expression “protocol message” must be understood here in the widest sense as referring more generally to requests or associated responses exchanged in the context of setting up a connection between the terminal and the service manager, instructions, audio, video data or text exchanged between the terminal and the service manager during execution of the service. Each message conforms to an appropriate protocol (SIP, etc.).
Such networks also include routing means whose main function is to receive protocol messages from a service manager or from another terminal of the same network or a third-party network and forward them to a terminal, or conversely receive protocol messages from a terminal and to forward them to a service manager or to another terminal. In an IMS network, for example, the routing means are generally part of an input manager also having terminal identification, connection, or disconnection functions. The input manager of an IMS network according to the 3GPP 23.002 standard thus groups together all the I/P/S-CSCF (Interrogating-, Proxy-, Serving-Call State Control Function) functions. The protocol messages can be based on the Session Initiation Protocol (SIP), for example, or any other appropriate protocol, as a function of the type of protocol message.
In such networks, a problem of conflict can arise during parallel or successive execution of a plurality of services for different service managers. For example, executing a second service can modify a protocol message of a first service that is being executed, leading to a malfunction or even an interruption of the first service, or the execution of a second service may be inappropriate during the execution of a first service.
This applies if the fun tone service and the click to dial service are activated in parallel, for example.
The fun tone service enables a subscriber using a called terminal to cause a user of a calling terminal to hear a particular tone if the calling terminal has requested to be connected to the called terminal and is waiting to be connected to the called terminal; thus while the called terminal is ringing to indicate the arrival of a call, the calling terminal receives a particular tone chosen by the user of the called terminal.
The click to dial service enables a subscriber to request, via a first terminal (the first calling terminal, for example a PC), that a second terminal (the second calling terminal, for example a telephone) be connected to a terminal of another user (the called terminal). To this end, when the first calling terminal requests connection of the second calling terminal to the called terminal of the other user, the service manager of the click to dial service first rings the first calling terminal and then, after the user has picked up the first calling terminal, causes the called terminal of the other user to ring.
If a calling user subscribes to the fun tone service and to the click to dial service, a problem arises if, for example, the user requests via a first calling terminal that a second calling terminal be connected to a called terminal of another user. In this situation, the first calling terminal activates the click to dial service manager that initially causes the second calling terminal to ring. The second calling terminal receiving a connection request activates the fun tone service manager, which then sends a particular tone to the second calling terminal, i.e. to the click to dial service manager. Sending this particular tone is of no use, in particular because it provides no service to users; it can also lead to a malfunction of the click to dial service manager, which is not designed a priori to receive such tones.
If the same application manager is able to provide a plurality of services, it generally includes, in addition to the service managers, a conflict manager that groups together all the rules for resolving potential conflicts between all the services available via the application manager.
A first drawback of such conflict managers is that they must be modified if conflicts occur with services of other application managers. Such modifications can prove difficult to implement, in particular if the application managers are the property of different service providers having divergent economic interests.
A second drawback of such conflict managers is that they necessarily group together a very large number of conflict resolution rules, an exponential function of the total number of services present on the network. Also, if a conflict occurs, it is necessary to choose between a very large number of rules for resolving the conflict.
To alleviate the first drawback, the 3GPP 23.002 standard, which defines all functions of the elements of an IMS network, provides a service capability interaction management (SCIM) conflict manager installed in the network independently of the application managers. The function of the SCIM conflict manager is to manage any conflicts between two or more service managers. However, since the standard gives no information either as to how conflicts must or can be managed or on how to implement the conflict manager, it provides no practical solution for alleviating the second drawback. In practice no existing communications network has any such conflict manager.